Catalytic polymerization of olefins with hydrogen bromide promoter



Sept. 12, 1950 D. J. ORIOLO 2,521,939

CATALYTIC POLYMERIZATION 0F OLEFINS WITH HYDROGEN BROMIDE PROMOTER FiledMay 22, 1948 COLD BATHS' Dorm'nzic v; Oriole INVENTOR.

AGENT I This invention relates to theQcatalytic jrkilymerization ofolefins and relatesmoreperticw' larly to processes ior'thepolymerization .ofJo'Ieflnswith a metal, halide catalyst 'where the acetivity of" the catalyst is enhanced byf'means of a hydrogenbromide'promoterg i It is well known that oleflns, such as propylene,the butenes th'e 'pentenes, etc.,. may be. polymerized in thepresencelol' catalysts such as the metal halides t0 brodiicelpolymerproducts having viscosities which make them, useful as lubricating oilsor as'blending agents for lubri; eating oils. It is also knownthattheactivity ofjthe metal halide catalysts may. be'enhanced byemploying a catalyst promotingagent where; byjthe viscosity of thepolymer jprodu'ct may be increased; Thus, hydroge bromide jlu'asivv beenemployed as, a catalyst. promoting agent r013 aluminum bromidecatalystin the polymeriz tion of various t pes of'oleflnsfor the'pur'p 2of obtaining pol mer mducts r higher cosityb It is an obiect'oi. thisinvention to-increase the promoting efiect of'hydrogen'bromide promoter}in olefin polymerization reactions. It' isfaffur' ther object of thisinvention to. increase the viscosity of olefin polymer products obtainedby'the polymerization of olefins in the presence of metal halidecatalyst and hydrogen bromide promoter. Itiis another-objector theinventionzto obtain polymer products of clear, brightcolor. It.isanother object of this invention-to provide animprovedoleflnepolymerization proc I ess. Itis anotheriobjectfiof thisinventionta provide an-olefln -polymerization process-wher'e by erratic;results 'with respect tothe viscosityof the polymer product areminimized; Further objects: of: the invention win become apparentIromathefollowing description thereoiif :In accordance with theinventiomolefins are polymerized in the presence of metal halidecatalyst and hydrogen 1i bromide pi6inGter' by processfwhich includes 3its es'se'n'tial 'st'e'p the treatment oi the -hydrogen -bromidepromoter to remove iron-bromide therefrom ju'sfiprior to ad ditionto the 'polymerization i'eactionr'niiit a It has 1 been discovered that}in the" "p" nlet ization'ofoleflns with -"mfetal '-haIide 'catalyst ndhydrogen bromide promoter, pretreatment of a1 hydrogen bromide promoterto"remove-"impurb" ties, particularly iron bromide, therefrom prior toaddition 01' the promoter to t I tion' reactionfimixtur suits e crease-mme" viscosity of the" polymer "produc obtained. It has further beendiscovered that.

rlyg rork v r AiiPIIcationMarZZ, 1948,;seria1 1q y such. r tment; tthe do n 1 bro ide r mo rn i n-t Q QnvIQ-thQ lym i e-j lon r a n mi re -underfi ed: l m rizaon: e ti n cond mp tem ture atat 2, 2c n r ,0 8 brom decon enr tuit ntc-v. u i rm es l ed-wi h r ectto h v e t e; Polym r :r rouct ey ta neq, d t 0ua1 y.-,n m rducts o a unifomly clear, brightappearance are obtained, Evid n in imne i emar cu ar i n brom ethough insmaller {even minute amount, have a poisoning eilfect on the activityof. the hydrogen bromide. promoter-reducing the viscosity of a the Palmr Pmdue nd he w p -e iv i e wit h mmm 01 pu ie the-h g qm Premier ing re "t :e at resu h iewed-s9 thedu t-= e 1te u i 1Q cansfitiqn 9 1 mpeure; tai 5 l fi ltmflenee dWW ement? mm." Additionally; the impuritiesaffect f -the color; of, the polymerw produci .,'.v producing-polymers-"of dark hirer, Byuthe; p'rocesshf: the invention, theseadverse eflects are not encountered.

In the commercial. manufacture oihydr'bjgen bromide, ron or iron alloy v.Qequipme'nt, is employed, and by reaction of the hydrog'en" bromidewith the 1r n ,1r onfl rommef is forrned ,By the procedures H or,manufacture; even ,though i this I iron bromide'may be 1 r ge1yr movea,particular at nt v may m 'belna fifim e ribvin eile traces ofthis-i1npurity.,. Further, hydrogen bromideis stored and shipped 5m ironor iron alloy e ili id efi iri ft e fiimet he dm enibmmlde. is +1 1 1 yn e i r ac ion ime pl ekl mr u e i qn-mbr m d while .hyd f rqm der dmnai el d let ri us impurit s Thus; free .01 ay he produced, vby the priorto; use lni polymerizatio cyl sure. purification treatment may beconven- 3 iently eflfected by flash distillation at atmospherictemperatures. A plurality of flash distillations, with successivereduction in pressure, is employed to insure maximum removal ofimpurities. However, distillation by the application of heat, atatmospheric, sub-atmospheric, or super-atmospheric pressures issatisfactory. Following purification, it is preferred to use thehydrogen bromide immediately to prevent the formation of freshimpurities. In this connection, the hydrogen bromide purificationoperation may be carried out jointly with the olefin polymerizationreaction. This may be done by passing the hydrogen bromide from thepressure cylinder or other source of supply as a feed stream for thepolymerization reactor to the purification operation, suclt as adistillation operation, and directly from the purification operation tothe polymerization reaction zone. Thus, the purification operation maybe made a component part of the polymerization process.

Hydrogen bromide promoter is ordinarily employed with metal bromidecatalysts although it may also be employed with metal chloride or othermetal halide catalysts. Its use is particularly effective with aluminumbromide catalyst, particularly aluminum bromide catalyst employed insolution in a saturated hydrocarbon. It may also be used with mixedmetal halide catalysts, as a mixed aluminum bromide-aluminum chloridecatalyst. I

The process of the invention is applicable in processes for thepolymerization of any type of olefin where hydrogen bromide promoter isemployed. Such processes include: the polymerization of propylene,l-butene, 2-butene, the isomeric pentenes, hexenes, etc. Other processesinclude the polymerization of diolefins, the copolymerization of twodissimilar mono-oleflns such as the copolymerization of propylene and abutene, or the interpolymerization of a monoolefin with a diolefin.

The accompanying drawing is a flow sheet schematically illustrating oneembodiment of the invention.

Referring now to the drawing. hydrogen bromide from a storage cylinderll provided with a valve H is led through line I! to flask is maintainedat a suitably low temperature, such as about -40 F. for example, bymeans of cooling bath I. High boiling material such as iron bromide isentrained in the flask and the hydrogen bromide is passed overheadthrough line It to flask il maintained at a low temperature by means ofcooling bath l9. Preferably, flask i1 is maintained at a lowertemperature than flask l4, such as a temperature of 60 F'., for example.Further high boiling material is entrained in flask l1, and the hydrogenbromide is passed overhead through line to filter 2| packed with amaterial such as glass wool to entrap any solid material which may becontained in the hydrogen bromide. The hydrogen bromide is then passedthrough line 22 to flask 2!. Flask 24 is maintained at a low temperatureby means of cooling bath 25 and preferably this temperature is lowerthan the temperature of flask II, for example, about "75 F. The hydrogenbromide is passed from flask 24 through line It to receiving vessel 21where it is maintained at a temperature of about -110 1". by means ofbath 29. Receiving vessel 21 may be maintained at substantiallyatmospheric pressure by being vented to the atmosphere through line ll.To prevent contamination oi the hydrogen bromide with air,

4 a slight positive pressure of dry nitrogen is maintained in the flaskby passing nitrogen into line 3. from line ii. The baths l5, l9, and 25may be, suitably, mixtures of solidified carbon dioxide and kerosene orsolidified carbon dioxide and acetone.

The hydrogen bromide in receiving vessel 21 is passed through line 32 topolymerization reactor 34 which may be of the reactor loop type. Passageof the hydrogen bromide to the reactor may be accomplished by closingvalve 35 in line 26 and valve 36 in line 30 and forcin the hydrogenbromide from the vessel by means of superimposed pressure of nitrogenfrom line 3 i.

An olefin polymerization catalyst, such as aluminum bromide dissolved ina suitable solvent such as normal butane or other low boiling saturatedhydrocarbon, is passed into the reactor through line 31. An olefin suchas propylene enters the reactor through line 39 and a diluent such asnormal butane or other low boiling saturated hydrocarbon enters thereactor through line 40. The reaction mixture is continuously circulatedwithin. the reactor 34 by means of pump 4 l, a suitably low temperaturefor the polymerization reaction being maintained by means of cooler 42.A stream of reaction mixture is continuously withdrawn from the reactorthrough line 44 and passed to a system for the recovery of the desiredpolymer product.

Polymer product may be recovered from the reactor by any suitable,conventional procedure. For example, the stream of reaction mixture fromline 44 may be washed with water to remove aluminum bromide catalyst andhydrogen bromide promoter. The washed mixture is then filtered throughclay, such as bentonite, which removes any catalyst and promoter notremoved in the washing operation and any impurities such as aluminumhydroxide formed by reaction of the catalyst with water. The filteredmixture is then fractionated for removal or diluent and catalystsolvent. A subsequent distillation, which may be under vacuum or a,steam distillation, may be had to remove light polymer product from thedesired heavier polymer product.

The following examples will illustrate the results to be obtained by theprocess of the invention.

Example I In this example, propylene in admixture with normal butane wasfed into a continuous olefin polymerization reactor along with aluminumbromide dissolved in normal butane. Hydrogen bromide promoter ofcommercial grade was also passed into the reactor by being admixed withthe entering feed stream of dissolved aluminum bromide. Analysis of thishydrogen bromide disclosed that it contained 1.34% by weight of ferrousbromide. Temperature of the polymerization reaction was maintained at-30 F. and the residence time was 23 minutes. A stream of reactionmixture was continuously drawn from the reactor and the mixture treatedfor removal of catalyst and promoter, filtered with bentonite clay,flash distilled for removal of normal butane and then steam distilled torecover the desired heavy polymer product from light polymer product.The recovered product had a 210 F. viscosity of 2504 saybolt Universalseconds and a N. P. A. color of 8.

I Example 11 In this example, the same procedures as in Example I werefollowed except that the hydrogen bromide promoter, prior to admixingwith the feed stream of aluminum bromide catalyst. was subjected tomultiple flash distillation in glass equipment substantially asdescribed in connection with the drawing. The polymer product obtainedhad a 210 F. viscosity of 3751 Saybolt Universal seconds and a N. P. A.color of 1%. It will be seen, therefore, that by the process of theinvention, an increase in viscosity of 50% and a decided improvement inthe color of the polymer product may be obtained.

Having thus described my invention, it will be understood that suchdescription has been given by way of illustration and example only andnot by way 01' limitation, reference for the latter purpose being had tothe appended claim.

I claim:

In a continuous process for effecting the polymerization of propylene,wherein a stream of propylene, a stream of aluminum bromide catalystdissolved in a non-polymerizing hydrocarbon, and a stream of hydrogenbromide promoter from a source of supply are passed continuously into apolymerization reaction zone; the improve- REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,382,753 Treseder Aug. 14, 19452,411,483 Wachter et al. Nov. 19, 1946 OTHER REFERENCES Leighton et al.:The Catalytic Isomerization of Paraiiln Hydrocarbons, Jour. Amer. Chem.Soc, vol. 65, pages 2276-2280.

